Solution Review: Problem Challenge 1
Quadruple Sum to Target (medium)
Given an array of unsorted numbers and a target number, find all unique quadruplets in it, whose sum is equal to the target number.
Example 1:
Input: [4, 1, 2, -1, 1, -3], target=1
Output: [-3, -1, 1, 4], [-3, 1, 1, 2]
Explanation: Both the quadruplets add up to the target.
Example 2:
Input: [2, 0, -1, 1, -2, 2], target=2
Output: [-2, 0, 2, 2], [-1, 0, 1, 2]
Explanation: Both the quadruplets add up to the target.
Solution
This problem follows the Two Pointers pattern and shares similarities with Triplet Sum to Zero.
We can follow a similar approach to iterate through the array, taking one number at a time. At every step during the iteration, we will search for the quadruplets similar to Triplet Sum to Zero whose sum is equal to the given target.